Stop a dog barking humanely
Are you suffering because your own or a neighbors dog is barking incessantly? then a citronella collar may be the solution.
Citronella collars for dogs are used to control incessant barking, fitted with a microphone they sense the dogs bark and spray them in the face with a citronella spray - something unpleasant for dogs since they don't like citrus smells.
So if you are suffering from a neighbors dog bark or your own dog has a barking problem - a citronella collar can be a good solution to train them into not barking. Another alternative is a electric shock collar - though these are less humane and less effective since the electric shock is too much of a irration to the dog and one it doesn't quite understand. So if your neighbors dog won't stop barking try asking the owner to use a citronella collar temporarily as a training mechanism.